Single direction coupling devices are used, in horology, for transmitting a movement of rotation in a single direction. They conventionally include two transmission members, one driving, the other being driven, which are secured to each other in a single direction of rotation and are uncoupled or detached in the other direction. Numerous single direction coupling devices are known to those skilled in the art, essentially between two transmission members with parallel or coaxial axes of rotation. Reference can be made to CH Patent Nos. 347 139, 493 874 and FR Patent No. 1 491 183 for further information on this type of coupling device.
Single direction couplings for transmitting a movement of rotation between two transmission members with concurrent perpendicular axes are also known. One example well known to those skilled in the art is the Breguet toothing coupling device, formed of two pinions each including a saw-like contrate toothing, cooperating with each other so as to mesh in a single direction of rotation, and uncoupled or detached from each other in the other direction of rotation. The two pinions are coaxial, but, in practice, the purpose of this coupling device is in fact to transmit a movement of rotation to a wheel whose axis is perpendicular to that of the pinions. Thus, the driven pinion generally includes a straight radial toothing, meshed with said wheel.
This type of coupling device is certainly highly efficient, but it is complex and expensive. In particular, the driven pinion including a Breguet toothing and a straight toothing, is a complicated part, which is difficult to manufacture.
It will be noted that this coupling device is mainly employed in a barrel winding device, in order to prevent activating the barrel in the opposite direction to the direction of winding. Thus, the winding device conventionally includes a sliding pinion fitted with a first Breguet toothing, mobile between a time-setting position and a winding position, and a winding pinion fitted with a second Breguet toothing, meshed with the sliding pinion in the winding position, and forming therewith a single direction coupling device. The winding pinion is also fitted with a straight radial toothing meshing with a crown gear wheel, which itself meshes with a ratchet mounted on a barrel. When the sliding pinion is rotating in a first direction of rotation, it meshes with the winding pinion, which drives the crown gear wheel. The latter in turn drives the ratchet, which winds the barrel. When the sliding pinion is rotating in a second direction of rotation, it is uncoupled or from the winding pinion, which is thus not driven in rotation, thus preventing improper manipulation of the barrel.